Motor-driven chain saws are known wherein the guide bar is mounted between the sprocket-wheel cover and the housing. For this purpose, stud bolts fixed on the housing extend through the guide bar and the sprocket-wheel cover and attachment nuts threadably engage the stud bolts at their free ends. When a saw chain is exchanged, the sprocket-wheel cover must be removed since the saw chain must be fitted into the guide groove of the guide bar as well as over the sprocket wheel for driving the saw chain. For this operation, the motor-driven chain saw lies on its side with the guide bar lying loosely on the side of the housing. The threaded bolts extend through the attachment protection of the guide bar. The guide bar can tip over the forward housing edge because of the projecting length thereof. The user must therefore support the forward end which, however, is difficult at the job site and is often not possible. The difficulty is always present that the guide bar will tip over because the operator needs both hands for mounting the saw chain whereby the exchange of the saw chain is made very difficult.